1. Field of the Invention
The instant disclosure relates to a touch system and the components of the touch system; in particular, to an optical lens and an image-capturing device applied in an optical touch system.
2. Description of Related Art
The existing touch control technology has already developed an optical touch system. The optical touch system commonly includes a plurality of image sensors and a plurality of infrared light emitting diodes (IR LEDs), in which the IR LEDs for example can be complementary metal-oxide semiconductors (CMOS) or charged-coupled devices (CCD).
The optical touch system has a contact plane for an object to make contact with. During the operation of the optical touch system, the IR LEDs emit infrared beams which are transmitted via the contact plane. When an object such as a finger or a stylus touches the contact plane, the object will block a certain number of infrared beams. As a result, shadows are generated on the contact plane. Meanwhile, the image sensors can detect the shadows. The optical touch system can use the shadows to calculate the position of the object on the contact plane and to further provide touch control.